There are various types of dispensing apparatuses for filling parenteral and opthalmic products into vials and containers. One such type is positive displacement fillers. These devices employ a cylinder and piston arrangement, which contacts and dispenses the fluid. Typically, fluid enters the cylinder as the piston is in its upward motion, which creates a vacuum into which the fluid enters through an inlet port. The downward motion of the piston expels the fluid through an outlet port. The process can then be repeated. Other embodiments of positive displacement fillers also exist, such as those using rotary pumps.
While these fillers are popular due to their speed and accuracy, their application is limited, especially in the pharmaceutical field. These devices are very difficult to clean, and typically must be disassembled to be sterilized. Also, since the device actually contacts the fluid, contamination is a constant risk.
Another type of dispensing apparatus is the time/pressure filler. These typically include a fluid chamber that is held under constant pressure. Fluid is dispensed through a discharge line, which is controlled by a pinch type valve. The valve is opened for a precise amount of time to dispense fluid. Since the pressure is held constant, and the time interval is constant, the amount of fluid dispensed should also be constant. However, due to variances in the equipment and deformation of the discharge tube over time, these systems are less accurate than required for many applications.
A third type of dispensing apparatus is the volumetric dispensing apparatus, as shown in U.S. Pat. Nos. 5,680,960, 5,480,063, and Publication No. 2005-0029301, which are hereby incorporated by reference. These devices measure and dispense a predetermined volume of fluid. These systems are highly accurate and avoid problems of contamination common with positive displacement apparatus, since there are no moving parts in contact with the fluid.
The above mentioned apparatus can all be used to dispense single-phase fluids but all of the apparatus described suffer from one or more significant drawbacks when dispensing solids dispersed in liquid (suspensions) or droplets of one liquid suspended in another liquid (emulsions). Suspension products, such as vaccines or steroid products may settle when not properly agitated. In the case of emulsions, the two liquids will form droplets when they are agitated but when agitation stops, the droplets may separate into two separate layers. Either of these cases will result in poor content uniformity from one vial to the next during the final dispensing of the product.
In addition, it can be difficult to clean the process equipment that has contained suspensions or emulsions, resulting in labor intensive cleaning procedures and significant downtime to change from one batch to another. Since the final drug product must remain sterile, rigorous aseptic processes must be adhered to in the reassembly of the dispensing apparatus.
It is therefore an object of the present invention to provide a dispensing system that has provision for the mixing of suspension and emulsion products, while maintaining the integrity of the system so that sterility is not negatively impacted. It is also an objective of this invention to minimize the amount of time spent cleaning the delivery system therefore minimizing the amount of downtime required.